1. Technical Field
The present invention relates to a virtual image display apparatus that presents images formed by an image display device or the like to an observer.
2. Related Art
As virtual image display apparatuses including head mount displays (hereinafter, referred to as HMDs) attached to heads of observers, binocular-type apparatuses provided with a pair of left and right display apparatuses and respectively projecting picture lights to both eyes are known (see Patent Document 1 (JP-A-2014-92696), Patent Document 2 (JP-A-2014-160112), and Patent Document 3 (JP-A-2010-48998)). In this case, if image display misalignment between left and right in binocular vision is significant (for example, misalignment of several pixels or more is produced), the observer may be difficult to continue viewing of pictures because recognition in perfect alignment of left and right images is impossible. Therefore, in the binocular-type virtual image display apparatus, it is very important that the pair of left and right display apparatuses are firmly positioned and fixed so that the relative misalignment between the apparatuses for right eye and left eye may not be larger, and have sufficient strengths so that distortion of the product or the like may not be produced after assembly of the respective parts.
Accordingly, for example, in Patent Documents 1, 2, the display apparatus for right eye and the display apparatus for left eye are respectively concentrically assembled to nearly one locations of a metal frame (for example, see FIG. 7 of Patent Document 1), and image display misalignment between left and right is suppressed with accuracy as optical systems maintained. That is, the accuracy and the strength are provided to the metal frame, and thereby, misalignment between left and right display apparatuses is prevented.
On the other hand, the observer wears the virtual image display apparatus, and thus, there are strong demands for reduction in weight and size. However, as described above, for example, to maintain the sufficient accuracy and strength in the metal frame, reduction in weight and size of the frame part is naturally restricted.